Category Archives: Digital

FT8, VHF and a side of W*TF

*Why

I’ve parked in worse places

For a hobby that’s been around for years, there’s always something new with amateur radio – and right now that thing is FT8. Released as a new mode as part of WSJT-X in 2017, it’s quickly become the dominant digital mode due to its ease of use, suitability for low signal environments and fast exchanges. Such is its popularity, the vast majority of spots currently submitted to PSK Reporter are FT8 (and you can see the current statistics here). For those familiar with other modes, the best way to describe it is as JT65 but transmitted by excited raccoons on crack, with each cycle taking just 15 seconds instead of JT65’s 60. This allows for a complete exchange from an initial CQ to the final 73 to take just 90 seconds. It’s definitely not a ragchewing mode though – again like JT65, each transmission is only capable of carrying a handful of characters – 13 in free text mode, and slightly more when using one of the predefined formats. Like most things related to amateur radio, it has its detractors (even I’ve moaned on Twitter about the effect it’s had on other digital modes), but that still doesn’t take away from the fun of having a new mode that makes it possible to make a whole bunch of contacts in sometimes less than favourable conditions.

*cue Enter Sandman*

Anyway, as fun as it is, there’s nothing more fun than pushing the envelope a bit. I’m not going to win any prizes for anything novel, but going a little bit outside of the norm is always good for a laugh. So, this past Saturday I decided to give 6m a try. Checking PSK Reporter showed a few stations monitoring 6m in and around the Pacific Northwest, so I dusted off the multiband vertical, stuck it on the roof of the truck and tuned it for 6m while sitting at my usual spot on Mt Tolmie. After a few tests to make sure nothing caught fire (did you know you can melt the glue around the relays inside a Z100 tuner? Neither did I), I set WSJT-X CQing.

And nothing happened.

And still nothing happened.

May not be an accurate representation of the circumstances

The weather was nice though…

Photo angled to hide garbage

And then finally, after about 20 minutes of not much happening, I got a response from VE7DAY, who after a quick QRZ search is in Campbell River – about 250km to the northwest. Signal reports were exchanged, and then a minute or so later I got another response, this time from VE7DXW in North Vancouver. I didn’t manage to get any more bites after these two, but it proves that even with a small setup, you can still have fun with VHF.

Not being one to settle though, later on Saturday – after a few well-received cans of cider – Jordan VA7TLZ and I wondered if we could manage an FT8 contact, but this time on 2m.

Dramatic reenactment, 4 cans of cider in

We’re about 4.5km apart, which would normally be easy, but we’re both in apartment buildings full of metal, and facing the wrong side of our respective buildings – Jordan facing south, and me facing west…

This was a stupid idea

But just because not every idea you have after a few drinks is a good idea, it doesn’t mean that all of them are terrible, because eventually…

What’s that coming over the hill?

…Jordan’s responses to my repeated CQs came through, and both of us now have an FT8 contact on 2m in our respective logs.

¯\_(ツ)_/¯

I guess the moral of this story is that just because it sounds like a stupid idea, it doesn’t mean that… okay fine, it was a stupid idea.

Recorded for posterity

Look forward to my next post, where we try moonbounce with stock antennas on a pair of Baofengs!*

 

* probably not, unless someone lets me at the liquor store again

First JT65 contact of 2017

Okay, so it’s probably the first JT65 contact I’ve had in more than a few years, but it’s definitely the first of this year.

I headed out this evening – a little later on than planned – to Mt Tolmie, put the 20m vertical on the roof of the truck and tuned the TS480 to 14.070, hoping to make some PSK contacts. Disappointingly, however, there was nothing to be heard. After listening around some of the other bands, I went back to 20m and listened up on 14.076, and heard the unmistakable sound of JT65.

As luck would have it, just last week I’d reinstalled wsjtx on the netbook that I use for radio, so given the lack of anything else to do fired it up and let it decode for a while. After some minor tweaking – namely correcting the time on the netbook, as JT65 is sensitive to incorrect clock settings – I saw a bunch of CQs decoded, including some from Australia and New Zealand.

Figuring that I may as well give it a try, I replied to one of them – VK4NJR in Queensland. Straight away they replied, giving me a signal report. I sent mine back, received the customary “73“, and into the log it went. It’s not every day you make a 12,000km QSO quite so easily.

Using WSJT-X to communicate with VK4NJR

If you’re not familiar with JT65, it’s a mode designed for low power and/or high noise situations. It’s a digital mode, using FSK (frequency-shift keying) to convey information. Because it can decode messages that are inaudible to the human ear, it relies on accurate clocks (at least to a few seconds) to make sure that each transmission starts at the beginning of a minute. Each transmission lasts for nearly the full minute, and in that time transmits a maximum of only 13 characters, which should give you an idea of how robust this mode is designed to be.

JT65 is part of a larger suite of modes developed by Joe Taylor K1JT, designed for weak-signal communication and for some of the more exotic methods of communication such as meteor scatter. For me, making a contact over such a long distance and with low power (in today’s case, around 5-10W) makes the whole thing a lot more fun.

Finally, there’s a really useful website if you’re working with JT65 called PSK Automatic Propagation Reporter. As the name suggests, it’s primarily aimed at collecting automated reports from people using PSK, but it’s also used for other modes – JT65 being one of them. It’s useful to be able to see where you’re being heard (or not, as the case may be) and I usually have it open somewhere while I’m on the radio.

pskreporter.info showing that I was heard in Australia, New Zealand and Brazil, amongst others!

Radio Weekends: HF digital modes

This Saturday, Josh VA7ACQ, Dom VA7CRO and myself stationed ourselves at various places around the CRD with the intention of running a few tests with various digital modes on HF. Dom went up to Sidney and Josh set up at Beaver Lake, while I headed for the usual spot down at Esquimalt Lagoon.

VA7CRO, VA7ACQ and VE7CXZ spread out across the CRD
VA7CRO, VA7ACQ and VE7CXZ spread out across the CRD

We settled on using 20m, hoping for a balance of less QRM and greater efficiency with the compact vertical antennas that Dom and I were using, while being not as useful for ground-wave as 40m may have been. After a bit of tweaking of audio levels and picking a dial frequency of 14.088MHz, Dom and I made contact with PSK31.

Working VA7CRO with BPSK31
Working VA7CRO with PSK31

Once we’d played with PSK31 for a while, we then moved to a much older mode by the name of Hellschreiber. Developed in the late 1920s, Hellschreiber (or Feldhellschreiber) sends text as a series of pixels, scanned left to right.

VE7CXZ, VA7CRO and VA7ACQ (in that order) working with Feld-Hell
VE7CXZ, VA7CRO and VA7ACQ (in that order) working with Feld-Hell

After this, we tried a whole bunch of other modes, including RTTY, MT63, Olivia, and MFSK – where Josh and I even managed to exchange small images! It was also a useful test of the RSID functionality in both FLdigi (which I was using) and DM780 (which both Josh and Dom were using), which sends a brief burst of MFSK before the actual transmission to both identify the mode being used and to centre the decoder on the right frequency.

I forgot to take any more screenshots, so here's another Feld-Hell one. You start to get a bit silly when you're sat in a cold truck at the seafront...
I forgot to take any more screenshots, so here’s another Feld-Hell one. You start to get a bit silly when you’re sat in a cold truck at the seafront…

Some findings from the afternoon’s experiments were that MT63 can be very particular about being on the correct frequency, that DM780 uses fixed centre frequencies for MT63 whereas FLdigi doesn’t, and – very much related to the first two – that the USB sound card I use for digital modes produces audio that is off by a not insignificant amount – about 40Hz.

By now it was starting to get a bit on the cold side, so we all made our way to Six Mile to warm up and for a much-needed beer.